Sedimentation apparatus



Dec. 20, 1955 s. i. BOUSMAN 2,727,628

SEDIMENTATION APPARATUS Filed April 23, 1951 3 Sheets-Sheet 1 IN VEN TOR.

SAMUEL aousMA/v A T TOR/VE Y Dec. 20, 1955 s. l. BOUSMAN SEDIMENTATION APPARATUS Filed April 23, 1951 3 Sheets-Sheet v 2 I N V EN TOR SAMUEL BOUSMAN 1; 4/ 4 T TORNEV Dec. 20, 1955 s. BOUSMAN SEDIMENTATION APPARATUS 3 Sheets-Sheet 3 Filed April 25 1951 gi m-M I l l |l|||||| Ill? SAMUEL BOUSMAN ATTORNEY 2,727,628 Patented Dec. 20, 1955 hiice SEDHWENTATION APPARATUS Samuel I. Bousman, Mountain View, Calif., assignor to Process Engineers Incorporated, a corporation of California Application April 23, 1951, Serial No. 222,457

Claims. (Cl. 210--55) This invention relates to sedimentation apparatus and particularly to thickeners or clarifiers in which solids suspended in a liquid are settled to form a sludge and raked to discharge. The rakes depend from supports within the clarifier, and the supports are driven to cause the rakes to sweep over the bottom of the tank. This application is directed specifically to improvements in the drive for the rake supports.

The present invention contemplates a settling tank, a column in the tank, and a sludge rake rotatably suspended in the tank to rotate about the column. The invention employs a combination comprising a horizontal turntable rotatably mounted to and supported by the column and carrying suspension means for the rake, an internal spur gear mounted on the turntable, a stationary yoke mounted on the column and overlying the turntable, and a prime mover supported by the yoke outwardly of the column and including a second spur gear meshed with the internal spur gear.

There are several basic requirements for a drive of the type under consideration, i. e. one mounted on a central pier. Thus such a drive unit should provide support for an overhead walkway extending from the center of the sedimentation tank to the outside rim. it must also include a member rotatable about the upright tank axis for driving the rakearm or arms, and it should be so designed that the walkway does not carry stresses developed in rotating the rakes, i. e. so that the reaction to this torque is supplied by the center column. Additional requirements are ei'liciency, durability and ease of maintenance.

Drives available heretofore have not met the requirements, at least to a satisfactory degree. They are met in full by the apparatus of the present invention, which is rugged, highly efficient and easily maintained, and does not impart torque to any of the superstructure of the sedimentation equipment. Moreover, bearing surfaces are reduced to a minimum, the entire rotating assembly resting on a single comparatively small diameter thrust hearing.

A feature of the present apparatus is the ease of assembly and disassembly, both the turntable and yoke being removable as units by lifting them ofi of the center column. The motor, employed as prime mover, is supported by the yoke by means of a special torque plate hearing, so that the torque from the motor is transmitted through the yoke to the central column. The walkway rests on the yoke at points opposite the motor to balance the weight of the motor, and is preferably anchored to the yoke by loose keepers so as to be ur1- affected by the driving torque.

Another feature of the preferred form of the apparatus is the relationship of the turntable, yoke and central column. In this form, the turntable is provided with a vertical hub journalled about the central column through an intervening bronze bushing. In addition, the yoke is arranged to fit closely over the turntable, both of these features serving to prevent the turntable from tipping under the influence of an unbalanced rake load. As a consequence, wear on the thrust bearing is minimized and the possibility of loss of bearing elements is avoided.

The invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. l is a sectional elevation of a sedimentation tank equipped with the apparatus of the invention;

Fig. 2 is an enlarged sectional elevation of the rake driving mechanism of the invention; and

Fig. 3 is a partial plan view of the apparatus of Fig. 2.

Fig. 1 shows a sedimentation tank 10 including a central vertical column or pier 12, an inlet conduit 14 opening into the bottom of the column 12, a sludge pit 15 and a discharge condiut 16 leading from the sludge pit. The central column 12 has a plurality of ports 12A, 12B, etc. from which influent introduced through conduit 14 is discharged into the upper portion of the sedimentation tank. The tank is also provided with a conventional overflow weir if in which clarified eflluent is collected and from which it is discharegd by conduit means (not shown).

Conventional sludge rakes 2G, 21 are supported by trusses or arms 20A, ZIA from a central cage 24 disposed coaxially with the column 12. The arms 20A, 21A extend radially from the cage. The cage 24 also includes radial trusses 26A, 268, etc., supporting a coaxial annular battle 26 which defines an inner treatment zone in which the influent issuing from ports 12A, 1233, etc, in the central column may be aerated by means not shown. Material from the inner zone flows under the baffle into the outer portion of the tank Where principal settlement occurs.

The present invention is directed to improved means for rotating the rakes 20, 21 through rotation of the cage 24 from a point above the liquid level in the sedimentation tank. The means for accomplishing this rotation of the cage 24 is best seen in the sectional elevation of Fig. 2 and the partial plan view of Fig. 3. These show that the central column 12 is provided with a cap 28. The cap is secured at its periphery to an annular flange 2) circumscribing and affixed to the upper end of the central column. An annular leveling or shim plate 30 is interposed between the cap 28 and the annular flange 2%. The leveling plate fail is adjusted in each installation to accurately level the upper surface thereof before installation of the drive unit so that cap plate 28, which forms a part of the drive unit, will be level upon installation. The cap supports a torque spindle 32 extending A upwardly therefrom and an annular machined seat 34 for an antit'riction thrust bearing 38, the spindle 3 2 and the bearing seat 34 being preferably coaxial with the central columnas illustrated. The spindle 32 may be integral with or separately supported by the cap plate 28. A turntable 36 having an impervious, relatively fiat plate surface 36?) is journalled on the spindle 32., a bronze bushing 37 being interposed between hub 36A of the turntable and the spindle. The turntable is supported entirely by the thrust bearing 38 mounted in the bearing seat 34 and supports the cage 24 at its upper end.

As shown in Figs. 1 and 3, the cage 24 is rectangular in plan and is supported from the turntable 36 at its projecting corners 36B, 36C, etc., the upper end of the cage being provided with gussets 39B, 39C, etc, for attachment to the respective projecting corners.

An internal spur gear or ring gear 40 is mounted. to the.

turntable 36, the spur gear being conveniently formed in angular sections joined by opposing vertical flanges 40%., 40B, etc. The sectional form of the internal spur gear,

in its preferred form, facilitates replacement of worn or defective gear segments if, and when, necessaryi A yoke 44 is keyed to the spindle 32 overlying the turn,-

table 36 and extends into the space defined by the internal gear .40 around the hub 36A of .the turntable. The yoke includes a substantially flat plate 44A and a peripheral vertical flange or rim 46 concentric with and within the confines of the internal spur gear '40. "The spur gear and flange form an annular channel which, in operation of the device, serves as an oil sump. An annular lip 48 affixed to the flange 46 and overhanging the gear 40 encloses the sump. An oil gauge 49 provides means for ascertaining the oil level in the sump.

A spur gear or driving gear 50 is mounted in a cavity in the yoke rim 46 between a lower guide bearing 52 supported by the yoke 44 and an upper pinion bearing 54 supported on an upper shoulder of the spur gear. The spur gear 50 is meshed with the internal spur gear 40. A motor '55 (see Fig. l) is connected through a Speed reducer 56 to the spur gear 50, the motor and speed reducer being supported independently of the spur gear.

The speed reducer 56, which supports the motor 55, is mounted on an indicating torque plate bearing or base member 58 of the angular contact type. The inner race 59 of the bearing is bolted to the yoke 44 around the spur pinion recess. The speed reducer is bolted to the outer race 59A and is thus free to rotate independently of the stationary yoke 44 within limits set by the allowable torque load. The torque plate bearing includes an arm 58A extending radially from the outer race 59A. The arm 58A is confined between a set pin 60A and a compression spring 60B of a load indicator 60 so that all thrust developed responsive to motor torque is received by the load indicator and transmitted through the yoke to the spindle.

The load indicator 60 comprises a base plate 62 afiixed to yoke 44 and supporting a cradle 60C in which the spring 60B rests. A bolt 63 traverses the spring and is held thereon at one end by a washer 64 and is journalled at its other end through a lug 65 against which the spring abuts. A screw 60D is threaded axially into the end of the bolt remote from arm 58A to engage switches 60B and 60F respectively. The switches control an alarm circuit (not shown) and a shut off circuit (not shown) respectively. By axial adjustment of the screw 60D, the thrust necessary to actuate the switches may be varied.

Operation of the load indicator is as follows: Motor torque due to the load of the cage and rake assembly develops a proportionate rotation of the motor mounting plate 59A and arm 58A against the loading of spring 6013. Displacement of the arm 58A against this spring loading displaces bolt 63 and pin 60D carried by the bolt, the load being transmitted through the spring to the lug 65, plate 62 and eventually to the torque spindle as described. If the load or torque exceeds a predetermined value the resultant displacement of pin 60D will actuate one or both of switches 60E, 60F depending on the extent of the overload.

It is important in an installation of this type to have an overhead walk to gain access to the centrally mounted drive mechanism for maintenance and repair. It is also important that this catwalk be free of any torque developed in the driving mechanism. This is accomplished in the present invention in the following manner:

A walkway 70 is supported at an outer end by the peripheral, wall of the tank (see Fig. l) and is supported at its inner end on the yoke 44.. The yoke 44 includes a number of radial reinforcing webs 44A, 44B, 440, etc., the webs 44A, 44B, and 44C forming a base for an integral horizontal web 45. Channel beams 74, 75 of the walkway 70 are supported on the web 45 and are retained thereon by keepers 76, 77 affixed to bosses 72, 73 on the webs 44A, 44C, respectively. A floor 78 laid acr ss beams 74, 75 furnishes the walking surface within the confines of a cylindrical cowling 80 forming a part of the walkway. The plan view of Fig. 3 is with this floor removed. The walkway rests on the web 45 and is held thereon by the loose keepers 76, 77, there being no rigid connection between the walkway and yoke 44. In this fashion torque transmission to the walkway is avoided. The walkway is held against lateral displacement by the keepers and against longitudinal displacement by the conventional anchor bolts at the tank wall. Beams 74, and cross arms 81, 82 are bolted to the cowling as illustrated.

All of the components of the drive are easily lifted from the torque spindle 32. To get at the bearing 38 for example, the fioor plate 78, beams 74, 75, and '81, motor, speed reducer, torque plate bearing and turntable are successively lifted from the torque spindle. Before removing beams 74, 75 by means of which the inner end of the walkway is supported on the yoke, it is necessary to block up the walkway either at the cowling 80 or radially outwardly therefrom. One suggested way of accomplishing this is by means of a beam inserted through the opening 12B in the top of column 12 and risers extending from this beam upwardly to support the walkway.

Under ordinary circumstances, the load on the thrust bearing 38 would probably not be sufiicient to keep the turntable from tipping under extreme unbalanced loads. However, the construction described provides two restraints on such undesirable displacement. The elongated hub 36A and the close fit between the yoke and turntable combine to prevent the turntable from tipping. As a result, wear on the antifriction bearing is held to a minimum.

The apparatus is lubricated as follows: Referring to Fig. 2, the annulus between the yoke casting and internal spur gear is filled with oil to a level determined by gauge 49 and may be drained through a bleed line 85. The bearing 38 is in a cavity which is filled with oil through the top of a pipe 86 passing coaxially through the spindle and also providing means for draining the bearing through a pet-cock 87. Bushing 37 is grease lubricated through a line 88. Oil from the spur gear annulus flows between the upper and lower surfaces of the turntable and yoke respectively and between the concentric vertical hubs thereof to the level determined by gauge 49. In this manner all of the moving parts of the drive mechanism run in oil or grease with a resultant durability and high eificiency.

I claim:

1. In sedimentation apparatus including a settling tank, means for introducing a liquid-solids mixture into the tank, means for withdrawing clarified liquid from the tank, and means for withdrawing settled solids from the tank, an upwardly extending column in the tank and a sludge rake suspended in the tank to rotate about the column, the combination which comprises a turntable rotatably mounted on and supported by the upper end of the column, the sludge rake being connected to the turntable to rotate therewith, a ring gear rigidly mounted on the turntable, a yoke rigidly fastened to the column and disposed above the turntable, a base member rotatably mounted on the yoke on an upright axis off center of the turntable, resilient restraining means connected between the yoke and the base member to restrict the rotation of the base member with respect to the yoke, and a prime mover mounted on the base member and provided with a driving gear meshed with the ring gear.

2. In sedimentation apparatus including a settling tank, means for introducing a liquid-solids mixture into the tank, means for withdrawing clarified liquid from the tank, and means for withdrawing settled solids from the tank, an upwardly extending column in the tank and a sludge rake suspended in the tank to rotate about the column, the combination which comprises a turntable rotatably mounted on and supported by the upper end of the column, the sludge rake being connected to the turntable to rotate therewith, an internal ring gear rigidly mounted on the turntable, a yoke rigidly fastened to the column and disposed above the turntable, a base member rotatably mounted on the yoke on an upright axis oif center of the turntable, a resilient restraining means connected between the yoke and the base member to restrict the rotation of the base member with respect to the yoke, a prime mover mounted on the base member and provided with a driving gear meshed with the ring gear, and switching means actuated by a predetermined degree of rotation of the base member with respect to the yoke for interrupting the action of the prime mover.

3. In sedimentation apparatus including a settling tank, means for introducing a liquid-solids mixture into the tank, means for withdrawing clarified liquid from the tank, and means for withdrawing settled solids from the tank, an upwardly extending column in the tank and a sludge rake suspended in the nk to rotate about the column, the combination vgzfh comprises a turntable rotatably mounted on and s ported by the upper end of the column, the sludge rake being connected to the turntable to rotate therewith, an internal ring gearrigidly mounted on the turntable, a yoke rigidly fastened to the column and disposed inside the ring gear but spaced therefrom to leave an annular oil sump the side walls of which are defined by the yoke and the ring gear, a base member rotatably mounted on the yoke on an upright axis otf center of the turntable, resilient restraining means connected be tween the yoke and the base member to restrict the rotation of the base member with respect to the yoke, and a prime mover mounted on the base member and provided with a driving gear rotatable around an upright axis and meshed with the ring gear.

4. In sedimentation apparatus including a settling tank, means for introducing a liquid-solids mixture into the tank, means for withdrawing clarified liquid from the tank, and means for withdrawing settled solids from the tank, an upwardly extending column in the tank and a. sludge rake suspended in the tank to rotate about the column, the combination which comprises a turntable rotatably mounted on and supported by the upper end of the column, the sludge rake being connected to the turntable to rotate therewith, an internal ring gear rigidly mounted on the turntable, a yoke rigidly fastened to the column and disposed inside the ring gear but spaced therefrom to leave an annular oil sump the side walls of which are defined by the yoke and the ring gear, a base member rotatably mounted on the yoke on an upright axis off center of the turntable, resilient restraining means connected between the yoke and the base member to restrict the relative rotation of the two, a prime mover mounted on the base member and provided with a driving gear rotatable on an upright axis and meshed with the ring gear, and switch means actuated by a predetermined degree of said relative rotation for interrupting the action of the prime mover.

5. In sedimentation apparatus including a settling tank, means for introducing a liquid-solids mixture into the tank, means for withdrawing clarified liquid from the tank, and means for withdrawing settled solids from the tank, an upwardly extending column in the tank and a sludge rake suspended in the tank to rotate about the column, the combination which comprises a turntable rotatably mounted on and supported by the upper end of the column and having an impervious relatively flat plate, the sludge rake being connected to the turntable to rotate therewith, an internal ring gear rigidly mounted on the rim of the plate, a yoke fastened to the column so that it cannot rotate and disposed inside the ring gear and having a substantially fiat plate adjacent a relatively large portion of the plate of the turntable and an upwardly extending annular flange spaced from the ring gear, the flange and the ring gear forming the sides of an annular oil sump, the bottom of the oil sump being formed by the plate of the turntable, and a prime mover disposed on the yoke and having a driving gear meshed with the ring gear.

References Cited in the file of this patent UNITED STATES PATENTS 2,021,304 Hardinge Nov. 19, 1935 2,140,059 Simonsen Dec. 13, 1938 2,291,836 Scott Aug. 4, 1942 2,467,409 Smith Apr. 19, 1949 2,557,316 Scott June 19, 1951 

1. IN SEDIMENTATION APPARATUS INCLUDING A SETTLING TANK, MEANS FOR INTRODUCING A LIQUID-SOLIDS MIXTURE INTO THE TANK, MEANS FOR WITHDRAWING CLARIFIED LIQUID FROM THE TANK, AND MEANS FOR WITHDRAWING SETTLED SOLIDS FROM THE TANK, AN UPWARDLY EXTENDING COLUMN IN THE TANK AND A SLUDGE RAKE SUSPENDED IN THE TANK TO ROTATE ABOUT THE COLUMN, THE COMBINATION WHICH COMPRISES A TURNTABLE ROTATABLY MOUNTED ON AND SUPPORTED BY THE UPPER END OF THE COLUMN, THE SLUDGE RAKE BEING CONNECTED TO THE TURNTABLE TO ROTATE THEREWITH, A RING GEAR RIGIDLY MOUNTED ON THE TURNTABLE, A YOKE RIGIDLY FASTENED TO THE COLUMN AND DISPOSED ABOVE THE TURNTABLE, A BASE MEMBER ROTATABLY MOUNTED ON THE YOKE ON AN UPRIGHT AXIS OFF CENTER OF THE TURNTABLE, RESILIENT RESTRAINING MEANS CONNECTED BETWEEN THE YOKE AND THE BASE MEMBER TO RESTRICT THE ROTATION OF THE BASE MEMBER WITH RESPECT TO THE YOKE, AND A PRIME MOVER MOUNTED ON THE BASE MEMBER AND PROVIDED WITH A DRIVING GEAR MESHED WITH THE RING GEAR. 